Safety equipment for fuel tanks



March 2, 1954 D, wHiDDEN 2,670,873

SAFETY EQUIPMENT FOR FUEL TANKS Filed Nov. 2. 1949 2 Sheets-Sheet 1INVENTOR.

ATTOEWB March 2, 1954 T. D. WHIDDEN 2,670,873

SAFETY EQUIPMENT FOR FUEL TANKS Filed Nov. 2, 1949 2 Sheets-Sheet 2 I 57W a? g m 3 L i L v "I I fl- I 43 I i j 40 d 4/ INVENTOR. IQ W///00A/ BYPatented Mar. 2, 1954 UN 1 TE!) STATES PATENT OFFICE SAFETY EQUIPMENTFOR FUEL TANKS Theron :D. Whidden, Jacksonville, Fla. ApplicationNovember 2, 1949, *Serial No. 125,139

:7 Glsims. (Cl.--220--88) This invention relates to safety devices andmore specifically to apparatus for protecting a tank containing aninflammable liquid or gas from fire or explosion. This application is acon tinuation-in-part of application Serial No. 646,921 filedFebruary11, 1946,1037 T. D. Whidden, now Patent No. 2,552,472, issued May -8,1951.

It is an important object of this invention to improve the safety oftanks containing inflammable gas or liquid, particularly the tanks ofbulk fuel delivery trucks and the like.

The conventional bulk fuel delivery truck tank has many fire andexplosion hazards. These tanks are customarily filled to a designated orpredetermined level or mark, leaving a portion of the upper section ofthe tank to be filled by expansion of the fuel. It is obvious that anyoverflow or leakage of the inflammable fuel constitutes a serious firehazard. Moreover, these tanks, through negligence, are often filledbeyond or above the designated mark, thereby taking up "all or a portionof that space intended as a safety factor and as a means for savingfuel.

Furthermore, these conventional bulk fuel delivery truck tanks haveanother disadvantage in that they have restricted vacuum relief whenunloading fuel, causing the operator to open the fill cap to relieve therestricted condition and this action increases the danger of ignition ofinflammable vapors which may cause an explosion.

Another common fault of conventional bulk delivery tanks is the constantdanger from sparks or fiame near their vents. No known existing trucktank arrangement provides posi tive flame arrestor action through thevents at all times.

Still another fault or fire hazard of such conventional truck tanksisthe extreme danger of refilling them due to the fact that when thetank has been unloaded the space formerly occupied by the fuel has beenreplaced by air and under certain conditions a mixture of fuel vapor andair is very explosive needing only a spark of any type (such as a staticspark or one caused by human negligence) to ignite it. The danger ofstatic spark is recognized to the extent that a chain is usuallyrequired by law to attempt to ground the static electricity. While ithas been suggested that the fuel be replaced by carbon dioxide or othernon-oxidizinggas, this is rarely done in practice due to the complexityor high cost of existing arrangements or to their unreliable action orto the necessity for their maintenance.

It is another object of this invention to reduce or eliminate theabove-mentioned disadvantages of fuel tanks for trucks.

The "above and related obie'cts are 'attained'in accordance with theinvention by providing various safety systems for protecting a tankcontaining an inflammable liquid or gas from fire or explosion. Thesesystems are particularly adaptable for bulk fuel delivery truck tanksbut may be used with other types of tanks as well. A feature of all ofthe systems disclosed herein is the provision of an expansion chamber ofpredetermined or calibrated size partially within the fuel tank. Thisreduces the height required for the installation.

In one exemplary embodiment of the invention, the expansion chamberpartially within the fuel tank has its inlet at a higher level than thefuel tank inlet (so that no fuel can enter the expansion chamber whilethe tank is being filled) and has its outlet (at the top of theexpansion chamber) connected to an auxiliary expansion'chamber at theside of the fuel tank. The auxiliary expansion chamber is positioned andconnected between two flame guard chambers partially filled with anon-inflammable liquid. One of the flame guard chambers is connected tothe exhaust pipe of the truck engine while the other is connected to theatmosphere. Each flame guard chamber is provided with a bell chamberhaving a multiplicity of small holes therein to reduce the size of thebubbles in the liquid.

If desired, the bulk fuel tank can have a divided construction and twoor more expansion chambers provided, one for each division of the fueltank. One of these modifications is provided with mechanical checkvalves while the other doesnot have such valves.

The invention will be more readily understood by referring to thefollowing description taken in connection with the accompanyingdrawings, in which:

Fig. 1 is an elevation view, with portions in cross-section, of a bulkdelivery fuel tank with an improved safety arrangement in accordancewith theinvention;

Fig. 2 is a top view of the arrangement of Fig. 1;

'Fig. 3 is an elevation View, with portions in cross-section, of amodification of the arrangement of Fig. l; and

Fig. *4 is an elevation view, with-portions in cross-section, of amodification of the arrange: ment of Fig. 3.

Referring more specifically to the drawings, Figs. 1 and 2 show, by wayof example for purposes of illustration, a bulk fuel delivery tank l0and safety apparatus therefor, in accordance with the invention, whichwill .be described below.

The tank T0 is, by way (if-example, of the type used by trucks for thetransportation of fuel bulk but it will be appreciated that certainfeatures of novelty of the present invention are applicable to othertypes of tanks as well. The tank I has a filler cap H and a withdrawalor delivery line l2 having a valve l3 therein.

The safety apparatus for the tank It will now be described. Positionedalmost, but not entirely, within the confines of the tanki t is anexpansion chamber It, the upper portion 65 of the chamber I4 extendingabove the filler opening closed by the cap H. A connecting line [5extends from the top part of the tank It almost to the bottom ll of thechamber 14. From the extreme top of the chamber M a pipe line I8connects with an auxiliary expansion chamber l9. From the top of chamberI9 a pipe line 20 extends into and nearly to the bottom of side chamber23 while another pipe line 22 connects from the chamber 28 to the top ofside chamber 23. The pipe 24 extends from thelower portion of chamber 23out through the top of this chamber to the exhaust pipe 25 of the truck.The pipe lines as and 2f! extend below the surfaces of the liquid (suchas glycerine) B ll and 31 in the chambers and 2%, respectively, and

are connected, respectively, to the bell chambers 25 and 21 therein.Each bell chamber has a multiplicity of apertures 23 therein. From thetop of chamber 21 a line 29 opens tothe atmosphere. The chambers l9, 2iand 23 and the connecting lines thereto and therefor are all external ofthe tank H3. The use of I 'ycerine is particularly valuable due to itsant reeae qualities and since it is mixable with water but not withgasoline. Its weight and viscosity also make it suitable for thepurpose.

The expansion chamber is is calibrated for a predetermined rate of fuelexpansion, such as 3 percent for example. Since the line it extendsabove the filler opening closed by the cap H,

even if the tank It! is filled completely full and 4- the filler cap isscrewed on tight, no fuel can reach the expansion chamber Hi during thefilling operation even if the operator is careless enough to overflowthe tank. For this reason, this predetermined margin of safety forexpansion is absolutely available even if the operator is careless ornegligent in filling the tank.

As the temperature rises and the fuel in the tank Ii) increases involume, the excess flows through pipe it into the expansion chamber 84.This displaces the air in the chamber is, causing an increased pressureof air in line it and also in lines 28 and 22. Thus, pressure applied tothe surface of the liquid in chamber 23 raises the level of the liquidin line 25 equal to the distance that an equivalent pressure forces theliquid down in line Eli inside of chamber As the pressure forces theliquid down further in line 29 into bell chamber 2?, air escapes throughthe openings 28, bubbling up through the liquid 31 and the line at tothe atmosphere. The purpose of the bell chamber 2? is to allow a largearea for many small holes 23 thus causing smaller bubbles and lessagitation or splash of liquid seal.

Consideration will now be given to the reverse operation, that is tocontraction of the fuel in the main tank iii or to the opening of thedelivery valve l3 (either of which will cause a partial vacuum in themain tank). This partial vacuum draws or lifts any excess fuel inchamber is back into the main tank it through line it. The same partialvacuum is applied to line (3, chamber l9, lines 22 and 2i) and lifts theliquid up in line 28 the same distance that it pulls the liquid leveldown in line 24 into bell chamber 25, thus opening the holes 28 andallowing the engine exhaust gases from the pipe 25 to enter. Any carbonor dust particles are trapped in the liquid in chamber 23 and settle onthe bottom of this charm her where they cannot interfere with passage ofgases. The chamber [9 acts as a trap for any splash of liquid seal fromeither chamber 25 or 23 to prevent it from entering the expansionchamber M. It also has the function of trapping any overflow (caused byexcessive expansion of fuel) from the chamber l i. Any fuel enteringchamber l9 will not return to the main tank l9 and examination of theamount of fuel therein will provide a reading, if desired, which can beused to ascertain whether the tank id is large enough for theinstallation. The chamber i9 can be drained by means of the opening 32.

The arrangement shown in Fig. 1 can also be used to force fuel from themain fuel tank HI by providing the out off valve 33 in the line 25.Since lines 24, 22, l3, I6, 29 and 29 are of equal size piping, which isalso the same as that used for the gas pipe 25, it is perfectly safe toapply the pressure of the engine exhaust to the tank ll). By closing orpartially closing valve 33 in exhaust pipe 25, the pressure of exhaustgas is routed through line 213, the liquid 3%, and line 22 to chamberl9. Pressure is built up to a point sufiicient to force glycerine downin line 25 into bell chamber 21, before escaping to the atmospherethrough the glycerine 3i and line 29. The pressure that was exerted inline 29 is also applied to line it and, of course, to the tank ii] andits contents. If the drain valve I3 is open and the gases are insumcientin volume to replace the liquid being drawn oil, the weight of theglycerine will close line 28. Speeding up the motor of the truck is notdangerous since this will again open line 26. Line 21), chamber 23,glycerine 3| and line 29 form a low pressure relief or check valve. Line24, chamber 23, glycerine 35 and line 22 form a low stage vacuum reliefor check valve. This feature of utilizing the compression of the exhaustengine gases to force fuel from the tank ii; is very valuable. It alsoprevents any possibility of explosion of the tank ME by flame, spark orstatic electricity. Since this arrangement will unload the bulk fuelmore quickly when the fill cap H is closed, the driver will have noreason to leave the cap off. Moreover, since the arrangement of Fig. 1can (by the pressure of the exhaust gas) lift the fuel to a deliverypoint higher than the level in the tank, in many cases it takes theplace of a delivery pump. It also has positive flame arresting oninhaling and exhaling openings and no mechanical check valves arenecessary since the liquid in the flame guard chambers 2i and 23 servesas liquid check valves. This liquid quenches any sparks which may bepresent if conventional pumps are used to force or transmit stack, flueor engine exhaust to the fuel tank.

Figs. 3 and 4 show modifications suitable for divided tanks but it willbe obvious that some features are applicable to single chamber fueltanks as well. In Fig. 3, the tank 10 comprises two divisions til andll. Partially-within each of the divisions is an expansion chamber 42(or iii). Each of these two chambers has an inlet pipe 44 (or 45)opening into the top of the fuel tank Iii and a drain pipe 36 (or 47)having a check valve M3 (or 49) therein. A drain 50 is provided for thetank l8 and the expansion charm bers 42 and 43 have their upper portionsconnected to the pipe 5| which is a vent line to.a flame guard chamberor to an auxiliary expansion chamber such as the chamber 19 in Fig. 1 oris opened directly to the atmosphere or to a source of carbon dioxidesuch as the pipe 24 in Fig. 1. Caps 52 and 53 are provided to fill thedivisions 40 and 4|. The expanded fuel flows into the chambers 42 and 13and when the fuel contracts it flows back into the tank Ill through thecheck valves 43 and 49. In the arrangement of Fig. 4, no mechanicalcheck valves are required as the pipes 6E: and 65 from the main tank Into the expansion chambers 42 and 43 are carried almost to the bottoms ofthe chambers 42 and 43. In this arrangement, the expanded fuel reentersthe tank 19 through pipes 39 and BI in a manner similar to thatdescribed above in connection with pipe iii of Fig. 1. Otherwise theoperation is the same as that of the arrangement of Fig. 3.

Various other modifications are possible without departing from thespirit of the invention, the scope of which is indicated in the claims.In the claims, the term gas is intended to cover a mixture of gases,such as air.

What is claimed is:

1. A safety system for a liquid fuel tank having a filler opening at theto thereof, comprising a closed expansion chamber at least the majorportion of which is within the confines of the outer walls of said fueltank, said expansion chamber being normally free of liquid, a connectionfrom the upper portion of said tank into the top portion of said chamberand extending to a point near the bottom thereof, a portion of saidconnection being at a higher level than said filler opening to prevententrance of liquid into said expansion chamber should said tank befilled to overflow said filler opening, and said top portion of theexpansion chamber having connections to the atmosphere for both pressurerelief and vacuum relief.

2. A safety system for a liquid fuel tank having a filler opening at thetop thereof, comprising a closed expansion chamber at least the majorportion of which is within the confines of the outer walls of said fueltank, a connection from the upper portion of said tank to said chamber,a portion of said connection being at a higher level than said filleropening, a flame guard chamber adjacent said tank and containingnon-inflammable liquid, means for admitting inert gas to said flameguard chamber, and pipe means for connecting said flame guard chamber tosaid closed chamber, said gas admitting means including a bell chamberhaving a plurality of apertures therein submerged Within the liquid ofsaid flame guard chamber.

3. A flame guard chamber comprising a closed tank adapted to containnon-inflammable liquid, an opening in the top of said tank, a secondopening in the top of said tank, a pipe adapted to have inert gasapplied thereto projecting through said second opening and extendingalmost to the bottom of said tank, and a bell chamber connected to thelower end of said pipe, said bell chamber having a plurality of smallapertures therein.

4. In combination, a tank adapted to contain an inflammable fluid, ahollow container which is normally free of liquid and which is at leastpartially within said tank, means connecting the upper part of said tankto the upper part of said container in such a way that fluid will notenter the hollow container should the filler opening be caused tooverflow and that when fluid in said tank expands or overflows it flowsinto said container, drain means in the lower part of said container fordraining fluid therein into said tank, said drain means having a checkvalve therein to prevent the entrance of fluid into said hollowcontainer through said drain means, and means for admittingnon-inflammable gas into said container when the fluid is being reducedin volume and for directing the flow of said gas from said containerwhen the fluid is being expanded.

5. A safety system for a liquid fuel tank having a filler opening at thetop thereof, comprising a closed expansion chamber at least the majorportion of which is within the confines of the outer walls of said fueltank, a connection from the upper portion of said tank to said chamber,an auxiliary expansion chamber at the side of said fuel tank, a pipeconnection from the upper part of said first expansion chamber to saidauxiliary expansion chamber, a flame guard chamber on each side of saidauxiliary expansion chamber, and pipe connections from the flame guardchambers to said auxiliary expansion chamber.

6. A safety system for a liquid fuel tank having a filler opening at thetop thereof, comprising a closed expansion chamber at least the majorportion of which is within the confines of the outer walls of said fueltank, a connection from the upper portion of said tank to said chamber,a portion of said connection being at a higher level than said filleropening, a liquid check valve chamber adjacent said tank and containingnoninflammable liquid, pipe means for connecting said chamber to top ofsaid closed chamber and pipe means for connecting and transmittingpressure relief to the atmosphere, a second liquid check valve chamberadjacent said tank and containing non-inflammable liquid, pipe means forconnecting said chamber to the top of said closed chamber, and pipemeans foradmitting inert gases into said second liquid check valvechamber and transmitting vacuum relief to said tank.

7. A safety system for a liquid fuel tank having a filler opening at thetop thereof, comprising a closed expansion chamber at least the majorportion of which is within the confines of the outer Walls of said fueltank, said expansion chamber being normally free of liquid, a connectionfrom the upper portion of said tank into the top portion of said chamberand. extending to a point near the bottom thereof, a portion of saidconnection being at a higher level than said filler opening to prevententrance of liquid into said expansion chamber should said tank befilled to overflow said filler opening, a second expansion chamber, aconnection from the top portion of said first expansion chamber to thetop portion of said second expansion chamber, and connections from thetop portion of the second expansion chamber to the atmosphere for bothpressure relief and vacuum relief.

THERON D. WHIDDEN.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 57,479 Church Aug. 28, 1866 57,866 Church et a1 Sept. 11, 186661,213 Knight Jan. 15, 1867 1,974,034 Pelleriti Sept. 18, 1934 FOREIGNPATENTS Number Country Date 381,409 Germany Sept. 20, 1923 398,524Germany July 15, 1924 467,334 Great Britain June 14, 1937

